Scientific Highlights

The interplay between a topological electronic structure and magnetism may result in intricate physics. In this work, we describe a case of rather peculiar coexistence or competition of several magnetic phases below seemingly single antiferromagnetic transition in LnSbTe (Ln = Ho and Tb) topological semimetals, the magnetic members of the ZrSiS/PbFCl structure type (space group P4/nmm). Neutron diffraction experiments reveal a complex multi-step order below T_N = 3.8 K (Ln = Ho) and T_N = 6.4 K (Ln = Tb). Magnetic phases can be described using four propagation vectors k₁ = (¹/₂ 0 0) and k₂ = (¹/₂ 0 ¹/₄) at a base temperature of 1.7 K, which transform into incommensurate vectors k₁′ = (¹/₂ – δ 0 0) and k₃ = (¹/₂ – δ 0 ¹/₂) at elevated temperatures in both compounds. Together with the refined models of magnetic structures, we present the group theoretical analysis of magnetic symmetry of the proposed solutions. These results prompt further investigations of the relation between the electronic structure of those semimetals and the determined antiferromagnetic ordering existing therein.

Li-rich nanoparticles of Li_1+xMn_2-xO₄ doped with Al, Co or Ni are successfully synthesized using a facile, fast and efficient microwave-assisted hydrothermal route. In this study, we demonstrate that nanocrystallinity and cationic doping play an important role in improving the electrochemical performance with respect to LiMn₂O₄ microparticles. They significantly reduce the charge-transfer resistance, lower the 1^st cycle irreversible capacity to 6%, and achieve a capacity retention between 85 and 90% after 380 cycles, with excellent columbic efficiency close to 99%.

This work aimed to produce intermetallic samples of platinoid metals (active metal matrix) and lanthanides (co-metal) and via the method of Coupled Reduction, i.e. a thermal treatment of the combination of the lanthanide oxide and noble metal at high temperature, as high as 1100 °C, under a constant flow of H₂. We have demonstrated by means of several techniques, such as Scanning Electron Microscope, Energy Dispersive X-Ray Spectroscopy, Alpha Spectrometry and Radiographic Imaging, that this method, at defined experimental conditions (temperature, pressure and concentration) yields a metallic lanthanide thin film when using platinum as active metal matrix. Conversely, the formation of a bulk intermetallic compound was obtained when using Pd as matrix. Those systems will have applications in different nuclear physic and radiochemistry studies, such as irradiation targets for production of superheavy elements and for nuclear data determination.

Chiara Favaretto, PhD student in the “Radionuclide Development” group at the Center for Radiopharmaceutical Sciences, received the NMB/Eckelman Young Investigator Award for the abstract entitled: “Production and radiochemical separation of terbium-155 from enriched gadolinium target material and its preliminary application in SPECT imaging”, presented at the International Symposium on Radiopharmaceutical Sciences (iSRS 2022).

Lithium-rich layered oxides, containing cobalt, despite being promising high-capacity cathode materials, need alternatives to eliminate toxic and geopolitically restricted cobalt. An ongoing search for low-cost, Co-free Li-rich cathode materials with a better structural stability lead to investigation of Li_1.16Ni_0.19Fe_0.18Mn_0.46O₂ (LNFM), where cobalt is replaced by abundant iron. Our LNFM not only delivered a high capacity of 229 mAh/g but also has a stable average discharge voltage when cycled to upper cutoff potential of 4.8 V in additive-free electrolyte.

In the cuprates, high-temperature superconductivity, spin-density-wave order, and charge-density-wave (CDW) order are intertwined, and symmetry determination is challenging due to domain formation. We investigated the CDW in the prototypical cuprate La_1.88Sr_0.12CuO₄ via x-ray diffraction employing uniaxial pressure as a domain-selective stimulus to establish the unidirectional nature of the CDW unambiguously.